A laser beam is a very strong beam of controlled light whose energy density is much larger than that of a light beam from an ordinary light source, and therefore, exposure of a living body to the laser beam raises the temperature of an exposed spot high enough to injure or damage the spot by heat or transform its protein.
Especially, eyes, which are the light sensitive organs, can be incurably damaged, and so it is very dangerous to radiate the laser beam directly onto one's eye. The laser beam is a very strong beam of direction-controlled light so that the light power remains as high in the distance as it is at the light source or laser, and therefore, radiation of the laser beam onto an eye even from a remote light source is still hazardous to the eye.
Therefore, it is of a great concern that a beauty treatment laser device that is to be handled by a general user for skin treatment or removal of undesired hair be equipped with very strict safety means for preventing inadvertent projection of the laser beam to light-sensitive organs, such as eyes.
In view of this, one object of the present invention is to provide a laser beam irradiation device whose control circuit is equipped with foolproof safety means, thereby assuring that a general user can use the device with absolute safety.